1. Field of the Invention
The present invention relates to a switching apparatus for selectively coupling a terminal device such as a facsimile system or a modem to a telephone set connected to a telephone line in response to a signal sent through the telephone line, thereby causing the terminal device to automatically communicate with a sending end.
2. Description of the Prior Art
Telephone lines are used for speech communication by means of telephone sets and data communication by means of a terminal device such as a facsimile system or a modem connected to the telephone lines. When a telephone set and a terminal device are connected in parallel to a single telephone line, a ringing signal cannot be differentiated as a ringing signal for speech communication with the telephone set or as a signal for data communication with the terminal device. For this reason, conventionally, a called party answers the telephone and manually couples the telephone line to the terminal device so as to perform data communication, or the terminal device is automatically coupled to the telephone line upon reception of the ringing signal. When the telephone line is automatically coupled to the terminal device upon reception of the ringing signal, the calling party cannot perform speech communication with the called party even if the calling party wishes to communicate since the telephone line is automatically coupled to the terminal device. In this manner, the telephone line connected to the terminal device can be used only for data communication.